1. Field of the Invention
The present invention relates to a method of erasing images recorded in an image recording medium capable of recording images therein and erasing the same therefrom by the application of heat thereto, and an apparatus for conducting this image erasing method.
2. Discussion of Background
Various kinds of image recording media capable of recording images therein and erasing the same therefrom by the application of heat thereto have been proposed.
Representative examples of such image recording media are (1) a reversible thermosensitive recording material comprising a support and a thermosensitive recording layer formed thereon, which thermosensitive recording layer comprises a matrix resin and an organic low-molecular-weight material dispersed in the matrix resin, as disclosed in Japanese Laid-Open Patent Application 55-154198 and U.S. Pat. No. 4,695,528; (2) a reversible thermosensitive recording material of the above-mentioned type with an improved reversible thermosensitivity by the addition of a variety of additives to a thermosensitive recording layer thereof as disclosed in Japanese Laid-Open Patent Applications 63-39378 and 63-178079; and (3) reversible thermosensitive materials of the same type as mentioned above, with additional layers being provided thereon for use in practice as disclosed in Japanese Laid-Open Patent Applications 63-39376 and 1-14079, and Japanese Laid-Open Utility Model Application 2-3876.
In these reversible thermosensitive recording materials, image formation and erasure are performed by utilizing their characteristics that the transparency of a thermosensitive recording layer thereof changes depending upon the temperature thereof. The principle of such image formation and erasure is described in detail in U.S. Pat. No. 4,695,528.
Various methods of erasing images recorded in such a reversible thermosensitive recording material have been conventionally proposed. For example, when the reversible thermosensitive recording material comprises a support and a reversible thermosensitive recording layer formed thereon, there has been proposed an image erasing method by which heat is applied to the recording material on the side of the thermosensitive recording layer, or on the other side thereof, opposite to the thermosensitive recording layer, by use of a heat roller, a thermal head or a one-side heating member. The latter method is disclosed, for example, in Japanese Laid-Open Patent Application 3-142279.
None of any of the above-mentioned conventional methods, however, can attain the formation of a completely and uniformly transparent state by erasing recorded images from the recording material in a short period of heat-application time.